INTRODUCTION The Brain Imaging Core is central to the integration of behavioral and biological research at the Waisman Center MRDDRC. It was proposed as a new Core and approved for the first time in the 2001 competitive renewal of the Waisman Center MRDDRC. At that time, however, the construction of the Waisman Center's North Tower (which houses the Brain Imaging Core) was not yet completed. Since April 2001, the Core has become fully operational and has achieved rapid and sustained growth in the number of MRDDRC projects supported and the range of services provided. For example, the Core is now averaging more than 55 paid hours of MRI scanning time/week. The 2001 P30 award for this Core was limited to two years of funding, at the end of which time the Core's progress was reviewed by NICHD and found to be exemplary. Therefore, the remaining three years of funding were awarded, as well as a supplement to the Core's budget because the funds requested in the 2001 submission were insufficient to fund the Core's operation. The supplement has supported the continued expansion of the Brain Imaging Core within the Waisman Center MRDDRC. This section of the application describes the Core's proposed objectives, the existing facilities and resources, the dramatic growth of the Core over the past five years, and current and proposed utilization of this Core. It should be emphasized that unlike many other MRDDRCs, which access imaging facilities located elsewhere on their campuses and which are controlled by other academic units, the Brain Imaging Core of the Waisman Center MRDDRC is housed within the Waisman Center complex and is fully integrated into and under the control of the MRDDRC administrative structure, which makes it possible to give priority to Waisman Center MRDDRC investigators.